A major part of the cereals intended for human nourishment in traditional processing is first processed in the ground state as flour, middlings or semolina in a dough form and only then in paste products (for cooking in water). Characteristic of this product group is the so-called gluten or protein framework which must be formed in the dough forming phase in order to provide the necessary strength for the subsequent processing and the finished products.
Also very popular is a multitude of special products which can likewise be prepared for human consumption, proceeding from the dough form, e.g. toasted, puffed or fried. In this category of special products it is also possible to use gluten-free or low-gluten raw materials such as maize, rice or potatoes, etc. In this case, for example, the properties of the thermally treated starch are made use of, instead of the gluten framework, in order that the finished products hold together. But in this case, also, a temperature which is substantially below 100.degree. C. is applied in the dough phase, that is, there is no cooking process.
It is common to both product groups, particularly those produced from cereals, that they are subjected beforehand to some kind of heat treatment for human consumption, so that the recovered as completely as possible through digestion.
In its natural, whole state, a cereal grain has a cellular structure. As far as the flour material is concerned, this consists primarily of starch in crystalline form (70-75% TS) and of protein (10-15% TS), wherein there are different types of protein, some of which settles on the starch crystals, some of which is deposited between the individual starch granules, and 10-15% water. In microscopic section through a cereal grain left in its natural state the protein or gluten framework which provides the entire grain with its high strength can be seen very clearly by means of dying methods used especially for this purpose. During the grinding process, the dark shell parts are removed from the cereal grains, which are a few millimeters in size, and, depending on the requirements, the flour material is produced in definite granulations of from 0 to 500 .mu.m. In so doing, the bonds which naturally exist between the flour and semolina particles are correspondingly destroyed.
The consumer expects classical paste products such as spaghetti, macaroni, noodles, etc. to be cooked in water within 7 to 15 minutes without a large portion of the starch passing into the cooking water and being thrown away with it. This can be prevented in that the outer covering of only a few starch gains is destroyed during the industrial processing, but also particularly in that a good protein framework is formed in the paste product during the dough formation and a large part of the protein enters into reticular bonds and locks in the starch grains. But in order for the required gluten framework to be produced, it must be ensured that the natural bonds still remaining not be destroyed or damaged and that new bonds be produced at all points of contact of the flour or semolina parts via the dough processing. This requirement gives the entire dough formation for paste products its determined character. Until the present time, there have been two widely recognized models for paste product dough production. One of these relates more to its realization in terms of apparatus. Semolina and water, as well as other additions, depending on the product, are poured into a mixing trough with a content of several hundred liters, possibly even 1000-2000 liters. The material is agitated and mixed with a paddle shaft for 10-15 minutes, so that the water and other additions are uniformly distributed through the entire amount of product and the individual flour and semolina parts are given sufficient time also to really absorb the water and so that the latter can penetrate into the individual particles. The uniform distribution and the water absorption thus make the aforementioned dwelling time of 10-15 minutes in a mixing trough compulsory. Product which is already moistened is removed from the mixing trough by means of transferring elements and guided into a screw press and kneading screw via a worm conveyor screw, which now, with the dough formation, should develop the gluten framework and should simultaneously build up a high pressure of 70-100 bar for the molding pressing. All experience has confirmed that the temperature of the products may not exceed 50.degree. C. at any time during the dough formation in order to form a good gluten framework, assuming that the raw materials are faultless.
In the second, more economical model, the development of the gluten framework is conceived of as a result of the processing of the dough accompanied by relatively high pressures in the press screw, partly as biochemical process, since bonds occur among living protein, but partly also as a mechanical positively-guided movement process in order to provide favorable positions of the protein for new bonds by means of spatial displacement of all particles. The biochemical process is a function of the temperature and of sufficient water being made available. Until the present time, it has sometimes been a matter of dispute as to which specific types of protein are predominantly active, particularly for the new bonds. In natural grain, the gluten protein already consists of fibrous molecular formations which provide the entire grain with its mechanical strength due to a large number of bonds. However, a portion of these bonds is destroyed by means of the grinding process and the production of flour and semolina particles. If an additional 10-20% water is now added to the dry raw material consisting of flour, semolina or middlings, etc. with a water content of 10-15% and the mass is subjected to a mechanical pressure deformation process, the fibrous protein molecules are stretched and new bonds are formed simultaneously via sulfur and hydrogen groups, part of which have settled on the protein molecules. To the extent that it is possible to produce the new bonds as completely as possible especially via the sulfur groups, the greater the extent to which the inherent strength of the original grain can be given back to the newly composed piece of dough, e.g. as paste product, along its entire cross section. But not only are new bonds produced in place of the natural bonds destroyed by means of the grinding process, they are also put into another form which is more suitable for mechanical processing (pressing) and subsequent thermal treatment (cooking) and which can be conceived visually as a spatial rubber band weave tissue. It is this which first gives the dough its inherent typical, elastic and plastic and non-sticky characteristic. If it is attempted to produce a dough with only 20% total water content, only an incomplete gluten framework can be constructed in the absence of sufficient water molecules independent of the kneading intensity. The paste products produced from this can form a dough clump in a short amount of time during cooking and, in this form, can be prepared as conventional paste products only in a poor manner. In addition, in products with insufficient protein framework, too much starch from the surface of the product is lost in the cooking water and the paste product becomes slimy and sticky on the surface.
In recent decades, very many attempts have been made to develop a simpler manner of managing dough precisely for paste products. In contrast to classic bread dough, paste product dough can be designated as dry dough with an average dough moisture of 28-35%. After pressing, the excess water (excess water quantity of 12-13%) must be removed again by means of a drying process, so that the product is storable. Bread dough has an average water content of 50-65%. A large portion of this water is evaporated during baking. However, a high percentage of water remains in the bread, which is why traditional bread in closed packaging is only storable for a few days at room temperature. Bread dough with a water content of 50-65% is designated here as wet dough. It is known even in cooking school that bread dough can be kneaded easier, particularly with less force (energy), because of the high water content.
Carrying over the "simpler" dough formation of wet dough to paste products would be economically senseless, since all additional water above the water required for the formation of the gluten framework and for giving it form would have to be evaporated again likewise by means of the thermal drying process, which is costly in terms of energy. All previous attempts at using a shorter, simpler dough producing method for paste products failed without exception, at least to the knowledge of the present Applicant, either because of inability to overcome technical problems or due to unacceptable damage to the quality of the end product. Also, due to given biochemical and physical factors, it may not be possible for a gluten framework which is insufficiently formed or damaged after the pressing to be "repaired" again by means of some kind of influences. In addition, if the product has heat damage, i.e. if the temperature of the product increased substantially above 50.degree. C. during the dough formation, it is also no longer possible to guide the same product through the dough stage and press it again. This is why breading flour produced from already baked bread is unsuitable for using again as bread baking flour or raw material for paste products. During the dough formation, e.g. for paste products, biological factors must be taken into account. This means that high demands are placed on the raw materials as well as on the operation of the installations so that no sources of infection for harmful microorganisms are maintained or further increased. Particularly high demands are made in the production of paste products in which egg is added to the paste products. The critical point in this respect was previously the trough mixer because of the partially unmonitored dwelling time of the product in the rather moist climate, which is also optimal for harmful microorganisms. Therefore, the highest demands were placed on the trough mixer with respect to hygiene. The frequent cleaning is particularly time-consuming. With the use of chemical cleaning agents the cleaning process is only shifted to the cleaning of washing water. In any case, this leads to increased operating costs as well as increased product costs and corresponding production losses.